Trocar anchor

ABSTRACT

Apparatus and methods for providing access to a body cavity without substantial loss of inflation gas therein. The apparatus includes an access assembly that has a tubular member having a proximal end, a distal end, an elastic portion interposed the proximal end and the distal end, and a lumen therethrough. An anchor sleeve is disposed coaxially over the tubular member and has a radially expandable region. The anchor sleeve is moveable between an axially elongated configuration and an axially shortened configuration and is biased toward the axially shortened configuration by a force exerted by the elastic portion of the tubular member. The axially shortened configuration corresponds to the anchor sleeve being in the fully deployed position. Methods for providing anchored access to a cavity within a patient are also disclosed.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of, priority to, and is a continuation of U.S. patent application Ser. No. 11/249,830, filed on Oct. 13, 2005 and entitled “TROCAR ANCHOR,” which is herein incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates generally to apparatus and methods for accessing the interior of the body for performing surgery, diagnostics or other medical procedures. In particular, the present disclosure relates to an access assembly having an expandable anchor to secure and seal the access assembly to the patient's body.

2. Discussion of Related Art

Minimally invasive surgical procedures have recently been developed as alternatives to conventional open surgery. Minimally invasive procedures, such as laparoscopy, involve accessing the surgical area inside a patient through a plurality of ports introduced into the patient's body. This type of procedure is generally less traumatic to the body than open surgery, since these ports tend to cause less tissue damage and blood loss as compared to long incisions made for open surgery. A working space is typically created to provide space inside the surgical area for instruments to operate. For example, in laparoscopic surgery, the abdominal wall is elevated away from the organs in the body cavity. This is usually accomplished by filling the body cavity with a gas, such as carbon dioxide, raising the abdominal wall. This process, known as insufflation, is typically achieved by inserting a large-gauge needle known as a Veress needle into, for example, the intra-abdominal cavity for the introduction of gas. To perform surgical procedures in the intra-abdominal cavity, the insufflation pressure must be maintained, and the abdominal wall must remain elevated from the organs in the intra-abdominal cavity.

Once enlarged, the cavity may be accessed by inserting a trocar and cannula assembly through the abdominal wall. The trocar is a sharp stylet used to provide an initial penetration and access opening in the abdominal wall for the cannula. The trocar is removed and the cannula remains in the body to provide access to the surgical site.

In an alternative method known as the “open laparoscopy” method or the Hasson method, access is established to the peritoneal cavity through a small incision on the skin of the abdomen, typically through the umbilicus. A special open laparoscopic cannula is inserted. The physician uses standard laparotomy instruments and grasping forceps to laterally enlarge the initial incision and to lift/separate the fascia. This procedure eventually exposes the peritoneum and places it under tension so that it can be carefully pierced. Once accessed, the physician can pass a gloved finger into the cavity accessing the relevant anatomy and confirming safe entry. Upon securing access, the physician inserts the cannula through the incision and continues with a standard laparoscopic procedure.

During the surgical procedure, the pressurized integrity of the peritoneal cavity or pneumoperitoneum must be maintained even though there is substantial movement of the cannula during surgery. Unfortunately, it is often difficult to maintain a proper seal between the cannula and body tissue at the initial incision point. Prior art devices have typically employed a conical shaped sealing sleeve generally constructed from a rigid material. Upon insertion into the incision, the sleeve engages the tissue along the thickness of the incision and the sleeve's conical geometry pushes or displaces outward the tissue surrounding the incision. The tissue's natural resiliency will then cause the tissue to try to return to the tissue's original position which creates a sealing force against the surface of the sealing sleeve. The sleeve is usually sutured to the skin at a depth and position where the tissue's resiliency provides sufficient compression to maintain a seal. Another device maintains the integrity of the gas seal and anchors the cannula to the body using an inflatable membrane at the distal end of the cannula. A sealing member is pushed against the exterior side of the body, capturing tissue between the sealing member and the inflatable membrane.

It is also known to provide access for a surgeon to introduce his or her hand into the body during laparoscopic surgery. Such a hand access port should also be anchored to the patient's body, while providing a seal around the incision.

Accordingly, a need exists for apparatus and methods for anchoring a cannula or other access member to a patient with minimum tissue trauma while still providing a positive seal.

SUMMARY

The present disclosure is directed to apparatus and methods capable of providing a gas seal against a percutaneous opening in a patient without the use of suturing, external adhesive devices, or an inflatable anchor. The apparatus of the present disclosure generally has an expandable anchor designed to prevent withdrawal of a surgical access device such as a cannula while maintaining pneumoperitoneum in the cavity. The anchor is integrated into the device design, will not rupture, does not traumatize the body tissue against which it anchors, and automatically deploys following placement into the patient.

In one embodiment, the apparatus of the present disclosure is an access assembly having a tubular member having a proximal end, a distal end, an elastic portion interposed the proximal end and the distal end, and a lumen therethrough. An anchor sleeve is disposed coaxially over the tubular member and has a radially expandable region. The anchor sleeve is moveable between an axially elongated configuration and an axially shortened configuration and is biased toward the axially shortened configuration by a force exerted by the elastic portion of the tubular member. The axially shortened configuration corresponds to the anchor sleeve being in the fully deployed position. Thus, an external force must be applied to the anchor sleeve to overcome the force exerted by the elastic portion of the tubular member and place the anchor sleeve in the undeployed position for entry in or exit from a percutaneous opening.

A method of the present disclosure for providing access to a cavity in a patient includes the method step of introducing a tubular body through a percutaneous opening in the patient's dermis. A radially expandable member mounted on the tubular body is axially compressed to radially expand the member. This expansion provides a seal against the internal surface of a patient's dermis. The cavity is insufflated with a gas to provide space in the abdomen for surgical instruments. The seal created by the expandable region inhibits loss of the gas through the penetration. A proximal flange on the tubular body may be advanced to clamp against the exterior surface of the patient's dermis.

These and other embodiments of the present disclosure, as well as its advantages and features, are described in more detail in conjunction with the text below and attached figures. Advantageously, the present disclosure provides apparatus and methods for anchoring a cannula to a patient with minimum tissue trauma while still providing a positive seal.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

FIG. 1 illustrates a perspective view of the access assembly in accordance with an embodiment of the present disclosure;

FIG. 2 illustrates a perspective view of the distal end of the access assembly in the undeployed position, in accordance with the embodiment of FIG. 1;

FIG. 3 illustrates a perspective view of the distal end of the access assembly in the partially deployed position, in accordance with the embodiment of FIGS. 1 and 2;

FIG. 4 illustrates a perspective view of the access assembly in the fully deployed position, in accordance with the embodiment of FIGS. 1-3;

FIG. 5A is a perspective view of an access assembly in accordance with a further embodiment of the disclosure;

FIGS. 5B-D are cross-sectional views of an access assembly penetrating the tissue of a patient in accordance with the embodiment of FIG. 5A;

FIGS. 6A-B are cross-sectional views of an access assembly penetrating tissue in accordance with another embodiment of the present disclosure;

FIGS. 6C-D are side elevational views of the distal end of an access assembly in accordance with the embodiment of FIGS. 6A-B;

FIG. 7 is a cross-sectional view of an access assembly having a self adjusting sheath in accordance with a further embodiment of the present disclosure;

FIG. 8 is a cross-sectional view of an access assembly with an undeployed anchor having an obturator positioned within the anchor such that the obturator stretches the elastic tubing in accordance with the embodiment of FIG. 7; and

FIG. 9 is a cross-sectional view of an access assembly with a deployed anchor in accordance with the embodiment of FIGS. 7 and 8.

DETAILED DESCRIPTION

Methods and apparatus of the present disclosure are directed towards providing access to a body cavity for surgical procedures. Specifically, methods and apparatus of the present disclosure substantially prevent substantial loss of insufflation fluids through an incision by providing an access assembly that can form a peripheral seal against the incision and anchor the access assembly to the body, while allowing surgical instruments to access the interior of the body during minimally invasive surgical procedures.

To reach a desired body cavity, the access assembly is inserted through a percutaneous opening in the patient's body, such as an incision through the abdominal wall. The access assembly must typically pass through the abdominal wall which includes the outer skin, a layer of fat, a layer of fascia or alternating muscle and fascia, and the peritoneum. The layers of fat and fascia may vary in thickness, depending upon the body location and whether the patient is asthenic or obese. The peritoneum is a strong, elastic membrane lining the walls of the abdominal cavity. Just below the peritoneum, lie several vital organs, such as the liver, stomach and intestines, and other sensitive tissues. This is typically the area that the access assembly is positioned to reach.

To perform surgical procedures in this area, the abdominal wall is lifted off of the organs by inflating the area with an insufflation gas such as carbon dioxide. This provides sufficient space for surgical instruments to maneuver. To prevent loss of this gas and loss of working space, the access assembly must provide a gas-tight seal against the abdominal wall while permitting a sufficient range of motion for the instruments and minimizing damage to the portion of the abdominal wall engaged by the seal.

Although the present disclosure is described with reference to a surgical procedure which includes a penetration of the abdominal wall, such description is made for illustrative and exemplary purposes. As those skilled in the art will appreciate, many other surgical procedures may be performed by utilizing the methods and materials described herein. Preferred embodiments of the presently disclosed access assembly, anchor and methods of using the foregoing will now be described in detail with reference to the figures, in which like reference numerals identify corresponding elements throughout the several views. As used herein, the term mesh is intended to encompass a broad range of structural configurations including, but not limited to woven and non-woven structures, fabrics, weaves, braids, knits and/or felts.

Referring initially to FIG. 1, a perspective view of an access assembly in accordance with an embodiment of the present disclosure is illustrated. The access assembly 10 of the present disclosure generally comprises a hub member 12 having a blunt sheath tube 14 extending distally therefrom. An obturator or a trocar, slides removably into a lumen 16 defined by the sheath tube 14.

The hub member 12 may be fitted with a pneumostasis valve (not shown) on a proximal end for sealably receiving a surgical instrument therethrough. The pneumostasis valve may be housed inside hub member 12 or otherwise attached to the hub member 12 by means known to one having ordinary skill in the art. The valve may be a flap valve, a duckbill valve, or a gas-restricting device of some other design, so long as it allows entry of a surgical instrument while reducing the loss of insufflation gas during the surgical procedure. The pneumostasis valve prevents loss of gas by automatically closing access to the sheath tube 14 when surgical instruments are being switched. Desirably, a second valve for sealing around the instrument is provided for minimizing the loss of insufflation gas while an instrument is inserted through the access assembly.

The sheath tube 14 has an expandable region 24. The expandable region 24 comprises an anchor sleeve 20 disposed coaxially over the distal portion of sheath tube 14. The anchor sleeve 20 may be retained on sheath tube 14 by an anchor flange 22, or the anchor sleeve 20 may be attached to a distal end of sheath tube 14. For example, the anchor flange 22 is tightened around anchor sleeve 20 to compress the anchor sleeve against sheath tube 14 to hold the anchor sleeve 20 in place. The anchor sleeve 20 is illustrated in FIG. 1 in an undeployed position. As will be discussed in further detail below, the resting position for anchor sleeve 20 is the fully deployed position. An outside force is required to maintain anchor sleeve 20 in the undeployed position.

FIG. 2 illustrates an isolated perspective view of the anchor sleeve 20 in the undeployed position, in accordance with the present disclosure. The anchor flange 22 is positioned around a proximal end of anchor sleeve 20 to compress the anchor sleeve against a sheath tube 14 to hold the anchor sleeve 20 in place. The anchor flange 22 is fitted around anchor sleeve 20 in a manner which will allow the proximal end of anchor sleeve 20 to slide distally along sheath tube 14. In that case, the anchor sleeve 20 is fixed around a circumference of sheath tube 14 at the distal end thereof. Thus, anchor sleeve 20 will expand to its normally biased deployed position, as illustrated in FIGS. 3 and 4. Alternatively, the proximal end of the anchor sleeve 20 may be fixed to sheath tube 14 and the distal end may be slidably held to sheath tube 14 by an anchor flange.

The prior art employs a variety of mechanisms, such as using a pistol grip advancing system or some other translating mechanism, to move and expand the anchor mechanism. The access assembly 10 in accordance with the present disclosure is automatically biased toward the expanded (deployed) position. Thus, when there is no external force holding the access assembly in the undeployed position, the access assembly 10 will return to the deployed position. For example, the access assembly may include a tube disposed around sheath tube 14 and having a distal end attached to the anchor flange 22. A latch at a proximal end of the assembly, holds the tube in a proximal-most position, retaining the anchor sleeve 20 in the undeployed position. Upon release of the latch, the anchor sleeve 20 moves to the deployed position.

In a further embodiment, the sheath tube 14 comprises a resilient and/or elastomeric material. The anchor flange 22 is attached to the sheath tube 14, without being slidable in the longitudinal direction. A trocar or obturator is arranged so as to engage the sheath tube 14, stretching the sheath tube in a longitudinal direction, when the trocar is inserted into the sheath tube 14. As the sheath tube 14 is stretched, the anchor sleeve 20 is elongated in the longitudinal direction, moving the anchor sleeve 20 to the undeployed position. Using the trocar, the distal end of the access assembly is then inserted into the body. Upon removal of the trocar, the anchor sleeve 20 returns to the deployed position.

The trocar, sheath tube 14, or both have structure for engaging the trocar with the sheath tube 14, when the trocar is inserted into the sheath tube 14. The trocar may have a flange or protrusion that engages a similar protrusion in the sheath tube 14. The sheath tube 14, trocar, or both may have a tapered shaped. The trocar and sheath tube 14 are arranged so that the trocar stretches the sheath tube 14, while permitting the cutting tip on the distal end of the trocar to protrude from the distal end of the sheath tube 14.

In a further embodiment, the anchor sleeve 20 is sufficiently flexible to collapse upon insertion in an incision. Thus, upon inserting the distal end of the access assembly into the body, the anchor sleeve 20 collapses. After the anchor sleeve 20 reaches the body cavity, the anchor sleeve 20 expands. Upon the removal of the access assembly from the body, the anchor sleeve 20 collapses, allowing removal with the application of a small proximately directed force.

FIGS. 3 and 4 illustrate progressive states of deployment of anchor sleeve 20. More specifically, FIG. 3 illustrates a perspective view of the anchor sleeve in the partially deployed position, in accordance with the present disclosure. FIG. 4 illustrates a perspective view of the anchor sleeve in the fully deployed position, in accordance with the present disclosure. As can be seen by analyzing FIGS. 2-4, as the anchor flange 22 moves distally, the anchor expands to form a peripheral seal between the access assembly 10 and a percutaneous opening in the abdominal wall. The anchor sleeve 20 comprises a flexible and/or elastic material and may comprise polymeric sheet materials, braided, woven, knitted and non-woven materials, and combinations thereof. The materials desirably comprise medical grade materials.

In a specific aspect of the present disclosure, the expandable region 24 is a non-distensible imperforate cylindrical surface preferably constructed from an elastomeric sheet covering a plurality of polymeric strands. Exemplary materials for the mesh material include braided polymer strands such as medical grade metals, PET, polypropylene, polyethylene, and the like. Exemplary materials for the elastomeric sheet include latex, silicone, thermoplastic elastomers (such as C-Flex, commercially available from Consolidated Polymer Technology), and the like. The braided material is braided in the shape of a cylinder, or otherwise formed into a cylindrical geometry, and, as mentioned, is translatably disposed over sheath tube 14.

The sheath tube 14 can be constructed from a variety of materials including stainless steel, composite filament wound polymer, or extruded polymer tubing (such as Nylon 11 or Ultem, commercially available from General Electric), and other materials known in the art. These materials have sufficient strength so that the sheath tube 14 will not collapse when inserted into the abdomen. Although specific dimensions vary depending on the surgical procedure, the sheath tube 14 typically has an outer diameter from about 4 mm to 20 mm and a length between about 5 cm and 15 cm.

Referring now to FIGS. 5A-5D, another embodiment of an access assembly 50 is disclosed. Access assembly 50 includes a sheath tube 54 and anchor sleeve 52. The sheath tube 54 is preferably configured to be self adjusting along its length. For example, sheath tube 54 may be of a telescoping design or it may be formed of an elastic material which will allow the sheath tube to stretch and contract in the longitudinal direction.

A short tip section of sheath tube 54 is illustrated in FIG. 5A. Prior to making the percutaneous opening in the patient, the anchor sleeve 52, which is made of a flexible and/or elastic material and may comprise the materials discussed above for anchor sleeve 20, is disposed on the patient's body and the sheath tube 54 extends proximally from the anchor sleeve 52. Once the percutaneous opening has been made, the sheath tube 54 is at least partially inserted into the opening.

An expandable region 56 of anchor sleeve 52 is preferably formed of an elastic membrane layer and a plurality of polymeric strands, such as the braided polymer strands of anchor sleeve 20. In a specific aspect of the present disclosure, the expandable region 56 is a non-distensible imperforate cylindrical surface preferably constructed from an elastomeric sheet covering the braided material. Exemplary materials for the braided material include polymer strands such as medical grade metals, PET, polypropylene, polyethylene, and the like. Exemplary materials for the elastomeric sheet include latex, silicone, thermoplastic elastomers (such as C-Flex, commercially available from Consolidated Polymer Technology), and the like. The braided material is braided in the shape of a cylinder or otherwise formed into a cylindrical shape and disposed over the sheath tube 54.

The anchor sleeve initially has the shape of a circular sheet. An outer member 53 is desirably attached to anchor sleeve 52 and is preferably formed of a relatively rigid material, as compared to the anchor sleeve 52, so as to hold the anchor sleeve 52 on the outer surface of the body. The outer member 53 may comprise an annular member 60 of at least semi-rigid material to assist in maintaining a circular configuration for anchor sleeve 52.

In use, and with continued reference to FIGS. 5A-D, the access assembly 50 is placed on the patient's body, as illustrated in FIG. 5B. In order to access the abdominal cavity, for example, a trocar device 62 is inserted into a proximal end of sheath tube 54. As discussed above, at rest, the access assembly 50 is in the fully deployed position, as illustrated in FIGS. 5A and 5B. Trocar device 62 is arranged such that, when it is inserted into a proximal end of the lumen defined by sheath tube 54, the trocar device engages the distal end of the sheath tube 54, thereby stretching the sheath tube 54 to a point where the anchor sleeve 52 collapses to a cylindrical shape with a diameter approximating the diameter of the trocar device 62. The trocar device 62 extends beyond the distal end of anchor sleeve 52 to form an opening in the skin of the patient. As illustrated in FIGS. 5C and 5D, a point or cutting edge of trocar device 62 extends beyond the distal end of the sheath tube 54 and anchor sleeve 52, so that the trocar device 62 penetrates the patient's skin and can advance into the underlying tissue of the abdominal wall. Once an opening is formed in the abdominal wall 58, trocar device 62 is removed from sheath tube 54. When the force of the trocar device 62, the sheath tube 54, which is holding anchor sleeve 52 in the undeployed position, retracts and anchor sleeve 52 returns to its deployed position. The opening in the abdominal wall holds the proximal end of the anchor sleeve 52, while allowing the anchor sleeve 52 to bulge outwardly at the distal end of the access assembly. Accordingly, in the deployed position, anchor sleeve 52 extends radially and exerts a force upon an inner surface of the patient's abdominal wall 58, thereby forming a seal which will prevent insufflation gas from escaping around the outer circumference of sheath tube 54.

To facilitate insertion of the access assembly into a preexisting percutaneous opening, a surgical instrument such as, preferably, a blunt obturator (not shown), is inserted into the sheath tube 54. A blunt obturator is preferred for the reason that it will tend to minimize the trauma to the location of the insertion of the access assembly through the percutaneous opening. As discussed above, at rest, the access assembly 50 is in the fully deployed position. Accordingly, a surgical instrument having a suitable diameter must be inserted into a proximal end of the lumen defined by sheath tube 54. Having a suitable diameter will permit the obturator to engage the distal end of anchor sleeve 52, thereby stretching the anchor sleeve to a point where the anchor sleeve 52 collapses to a cylindrical shape approximating the diameter of the blunt obturator. At this point, the access assembly 50 may be inserted through the percutaneous hole formed in the abdomen of the patient. Finally, the obturator is removed from the access assembly 50 and the anchor sleeve 52 will return to the fully deployed position, in response to the force of the sheath tube 54, thereby forming a peripheral seal against the inner surface of dermis 58 to prevent the loss of insufflation gas.

After the access assembly 50 is secured and peripherally sealed around the opening in the patient, the blunt obturator is completely removed from the sheath tube 54 so that surgical instruments (not shown) can be inserted into the lumen of sheath tube 54 to access the body cavity below.

In removing the access assembly 50 from the body, the anchor sleeve may be collapsible so that a small proximally-directed force can pull the access assembly 50 out of the incision. Alternatively or additionally, a trocar or blunt obturator may be used to stretch the sheath tube 54 and collapse the anchor sleeve.

FIGS. 6A-D are side views of a trocar anchor penetrating the dermis layer of a patient in accordance with another embodiment of the present disclosure. This embodiment utilizes a step system to penetrate the dermis of the patient to allow the access assembly 70 to be inserted into the percutaneous opening. As the access assembly 70 is placed adjacent the dermis 78 of a patient, as illustrated in FIG. 6A, a tailpiece 80 of the access assembly 70 is inserted into the dermis 78 of the patient. The insertion of the tailpiece 80 into the dermis 78 provides stability to the remainder of the access assembly while also providing a pilot hole for the final percutaneous opening. Thus, the formation of the percutaneous opening and the insertion of an access assembly is achieved by a stepped approach.

Once the tailpiece 80 has been inserted into the dermis 78, in order to form a percutaneous opening large enough to accommodate a surgical instrument, a trocar device 82 is inserted into a proximal end of sheath tube 74. As discussed above, at rest, the access assembly 70 is in the fully deployed position. Accordingly, trocar device 82 has a suitable diameter such that, when it is inserted into a proximal end of the lumen defined by sheath tube 74, the trocar device engages the distal end of anchor sleeve 72, thereby stretching the anchor sleeve 72 to a point where the anchor sleeve 72 collapses to its smallest diameter. The trocar device 82 then continues down through the pilot hole formed by tailpiece 80 to form an opening in the dermis 78 of the patient. As best illustrated in FIGS. 6C and 6D, once an opening is formed in the dermis 78, trocar device 82 is removed from sheath tube 74. When the force of the trocar device 82, which is holding anchor sleeve 72 in the undeployed position, as illustrated in FIG. 6C, is removed, anchor sleeve 72 returns to its biased, deployed position, as illustrated in FIG. 6D. In the deployed position, anchor sleeve 72 exerts a force upon an inner surface of dermis 78, thereby forming a seal which will prevent insufflation gas from escaping around the outer circumference of sheath tube 74.

Referring now to FIG. 7, a side view of a trocar access assembly 90 having a self-adjusting sheath tube in accordance with another embodiment of the present disclosure is illustrated. The trocar access assembly 90 includes a anchor sleeve 92; an anchor base 94 which extends proximally from anchor sleeve 92; and an anchor flange 96 to prevent the access assembly from falling into the cavity of the patient. The anchor sleeve 92 is configured and dimensioned to form a peripheral seal around the percutaneous opening formed in the patient's body as it presses against the inner surface of the dermis of the patient. Similar to the embodiments described above, anchor sleeve 92 is predisposed to the deployed position by the self-adjusting sheath tube 98. An external force is required to alter the dimensions of anchor sleeve 92 such that anchor sleeve 92 is capable of being inserted into a percutaneous opening having a diameter which is less than the diameter of anchor sleeve 92 in the fully deployed position. Anchor flange 96 rests on an outer surface of the dermis of the patient around the periphery of the percutaneous opening.

A self-adjusting sheath tube 98 is disposed within trocar access assembly 90. Self-adjusting sheath tube 98 includes a tip portion 100, an elastic tubing portion 102, and a flange portion 104. Tip portion 100 forms the distal end of the self-adjusting sheath tube. Tip portion 100 is preferably formed of plastic. The elastic tubing portion 102 is connected at a distal end to the proximal end of the tip portion 100. Elastic tubing portion 102 forms the middle portion of the self-adjusting sheath tube 98. Flange portion 104 is connected to a proximal end of elastic tubing portion 102.

The distal end of anchor sleeve 92 is connected to a distal end of tip portion 100. Therefore, with reference to FIGS. 7 and 8, to insert the anchor sleeve 92 through a percutaneous opening in the dermis 112 of a patient, an obturator 110 or other instrument is inserted into the lumen defined by self-adjusting sheath tube 98. The obturator 110 is dimensioned such that it engages the distal end of tip portion 100. Upon further distal translation of the obturator 110, elastic tubing portion 102 elongates as a result of the force exerted by the obturator on tip portion 100. As tip portion 100 moves in the distal direction, anchor sleeve 92 is forced into the undeployed position, thereby forcing anchor sleeve 92 to have a smaller cross-section.

Once the trocar access assembly 90 is in position within the percutaneous opening formed in the dermis 112 of the patient, as illustrated in FIG. 8, obturator 110 is removed from the trocar access assembly 90 thereby allowing the elastic tubing portion 102 to return to its normal position. FIG. 9 illustrates the trocar access assembly 90 with the anchor sleeve 92 in the fully deployed position. Accordingly, in the deployed position, anchor sleeve 92 exerts a force upon an inner surface of dermis 112, thereby forming a seal which prevents insufflation gas from escaping around the outer circumference of sheath tube 98. Anchor flange 96 rests on an outer surface of dermis 112, to prevent the access assembly from falling into the cavity of the patient.

It will be understood that various modifications may be made to the embodiments disclosed herein. For example, although the above embodiments are described with reference to a surgical procedure implicating the abdomen, it is contemplated that the disclosure is not limited to such an application and may be applied to various medical instruments. Therefore, the above description should not be construed as limiting, but merely as exemplary of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims. 

1. A trocar access assembly comprising: an anchor sleeve; and an obturator insertable through the anchor sleeve; wherein when the obturator is inserted through the anchor sleeve, the obturator causes at least a portion of the anchor sleeve to be axially elongated and a radial cross-section of the portion of the anchor sleeve to become smaller, and wherein when the obturator is retracted from the anchor sleeve, the obturator causes the portion of the anchor sleeve to be axially shortened and the radial cross-section of the portion of the anchor sleeve to become larger such that the portion of the anchor sleeve having the enlarged radial cross-section engages an inner surface of an incision.
 2. The trocar access assembly of claim 1, wherein the expandable portion of the anchor sleeve is located adjacent to a distal end of the anchor sleeve.
 3. The trocar access assembly of claim 2, wherein the expandable portion of the anchor sleeve expands sufficiently to anchor the anchor sleeve within the incision.
 4. The trocar access assembly of claim 1, wherein the anchor sleeve is formed from an elastomeric material.
 5. The trocar access assembly of claim 1, wherein the portion of the anchor sleeve that is axially elongatable is biased to its axially shortened configuration.
 6. The trocar access assembly of claim 1, wherein at least a portion of the anchor sleeve provides a seal with the incision.
 7. A method comprising the steps of: providing a trocar anchor assembly including an obturator and an anchor sleeve; inserting the obturator through the anchor sleeve, the obturator causing at least a portion of the anchor sleeve to be axially elongated and a radial cross-section of the portion of the anchor sleeve to become smaller; inserting the trocar anchor assembly into an incision; retracting the obturator from the anchor sleeve, the obturator causing the portion of the anchor sleeve to be axially shortened and the radial cross-section of the portion of the anchor sleeve to become larger such that the portion of the anchor sleeve having the enlarged radial cross-section engages an inner surface of an incision; and inserting a surgical instrument through the anchor sleeve to perform a surgical procedure.
 8. The method of claim 7, wherein the portion of the anchor sleeve that is axially elongatable is biased to its axially shortened configuration.
 9. The method of claim 7, wherein the portion of the anchor sleeve that is radially expandable is formed from an elastomeric material. 